<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>

        function loadHtml(htmlurl){
            $("contentDiv").innerHTML = "<object type='text/html' data='"+htmlurl+"' ></object>";
        }

        function $(id){
            return document.getElementById(id);
        }
    </script>
</head>
<body>
    <span id="myspan">1.html</span>
    <input type="button" value="加载1" onclick="loadHtml('2.html')">
    <input type="button" value="加载2" onclick="loadHtml('3.html')">
    <div id="contentDiv"></div>
</body>
</html>